A plurality of development groups are studying wireless power transfer (WPT) systems for providing spatial freedom to energy transmitters and energy receivers. Analyses about coils coupled in various geometrical structures in terms of design and theory, geometrical optimization, and a common optimization approach using spiral coils having a plurality of layers of spirals or a plurality of turns have been dealt with in the related art. Optimization of power inducement of coils, in which no shielding elements are used and no wireless charging systems are applied, has also been dealt with in the related art. A method of providing uniform magnetic coupling between a transmitting (TX) coil and a receiving (RX) coil based on the size of the TX coil that is much greater than that of the RX coil has also been dealt with in the related art. It has already been proved that the uniform magnetic coupling between a TX coil and an RX coil enables power to be transmitted with uniform power transmitting efficiency (PTE).
WPT technology has been developed for mobile and wearable electronic devices in order to provide a convenient method for charging embedded batteries of the devices or a supply power connected thereto. Wireless chargers to which WPT technology is applied operate typically in the frequency range from 100 kHz to 100 MHz.
A wirelessly chargeable mobile device has a battery pack, and an RX coil mounted therein according to the related art. The wirelessly chargeable mobile device is charged when located in proximity to a TX coil of a wireless charger according to the related art. An induced electromotive force is generated in the RX coil by a magnetic field formed by the TX coil, and electricity induced from that electromotive force charges the mobile device.
The most common wireless power charger architecture is a star topology network. The wireless charger interacts with one or more mobile devices for simultaneous charging. Wireless coupling is achieved through a power TX resonator and a power RX resonator, and magnetically coupled inductive coils connect the TX resonator to the RX resonator. A power source is connected to the TX resonator, and the RX resonator is connected to a rectifier to transform energy from an alternating current (AC) to a direct current (DC) at the receiver side.
The major issue of long range and/or alignment insensitive wireless chargers is high level of electromagnetic interference (EMI) radiation. Large size, loosely coupled wireless chargers utilize high switching voltages and high currents in large-size primary coils, thereby posing EMI hazards to other electronic products.
The above information is presented as background information only, to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present disclosure.